A conventional example of the apparatus which fills a given amount of powder medicines into a vial or the like containers utilizes an auger screw (see, e.g., Patent Literature 1).
More specifically, as shown in FIG. 5, this conventional powder filling apparatus 51 comprises a funnel 52 which contains the powder, a funnel support 54 which supports the funnel 52 above a placing pedestal 53, a circular-cylindrical metering portion 55 provided at a lower end portion of the funnel 52, an auger screw 57 having a lower end provided with a screw portion 56, and a screw support 58 which supports an upper end portion of the auger screw 57 rotatably, wherein the funnel support 54 is fixed to the screw support 58 through a support column 59 and the screw portion 56 is arranged within the metering portion 55. The vial and the like container 60 is carried onto the placing pedestal 53 and placed below the metering portion 55. Upon the rotation of the auger screw 57, the powder within the funnel 52 is fed out of the metering portion 55 by a predetermined amount and filled into the container 60.
The auger screw 57 has an upper end portion to which there is attached a pulley 61 in association with a motor 62 attached to the screw support 58. The auger screw 57 has an axis of rotation made coincident with a center axis 64 of the metering portion 55 so as for the screw portion 56 not to contact an inner surface of the metering portion 55 when the auger screw 57 is rotated through this pulley 61. Further, as for a general powder filling apparatus, if the screw portion contacts the metering portion, the contact is not detected. Should they contact with each other, in many cases they are operated as they remain mutually in contact. However, the conventional art is equipped with a contact-detection means 65 which measures the exciting state between the metering portion 55 and the screw portion 56 so that the contact can be detected should both of them be brought into contact with each other.
According to the conventional art, it is required to make the axis of rotation 63 of the auger screw 57 precisely coincident with the center axis 64 of the metering portion 55 so as not to contact the inner surface of the metering portion 55 with the screw portion 56. This entails the following problems.
(1) The funnel must be precisely positioned for installation at a predetermined position where the center axis of the metering portion is coincident with the rotation axis of the auger screw. However, since this funnel is supported on a funnel support, which is a member separate from the screw-support portion, it is not easily positioned nor readily assembled because it should be installed to the funnel-support without any backlash.
(2) The funnel support is connected to the screw support through a vertical support column. This invites a necessity that the support column, the screw-support portion and the funnel-support have to be made robust so as not to produce strain or the like torsion therebetween with the result of causing problems that the equipment becomes large and besides it can be hardly put into practice at a low cost.
(3) Being vertically long, the auger screw needs to be supported by the screw-support portion at two points, one of which is a vertical intermediate portion and the other of which is an upper end portion, so that the rotation axis does not become eccentric. Further, it is preferable to lengthen a distance between both the support points as much as possible. This makes the vertical length of the screw-support portion large to result in causing another problem of enlarging the whole equipment much more.
(4) Additionally, the conventional art is provided with the contact-detection means which measures the exciting state between the screw portion and the metering portion so as to detect the contact therebetween. In normal operation when they don't contact with each other, it is necessary to insulate the funnel with the metering portion and the auger screw with the screw portion from each other so that the contact-detecting means cannot detect the exciting state of both of them. However, the funnel and the auger screw should be precisely positioned and fixed, respectively to the funnel support and the screw-support portion different from each other. This necessity requires to fix the support column 59 to the screw-support portion 58 through a circular-cylindrical insulating member 66, for example, as shown in FIG. 4 and therefore the funnel and the screw portion are not easily insulated.    Patent Literature 1: Patent Application Laid-Open No. 64-84801